/* trees.c -- output deflated data using Huffman coding
 * Copyright (C) 1995-1998 Jean-loup Gailly
 * For conditions of distribution and use, see copyright notice in zlib.h 
         
   file modified by Dimitre Trendafilov (2003)   
 */

/*
 *  zdelta: the following paragraphs are updated to match libzd features
 *
 *  ALGORITHM
 *
 *      The "delta_deflation" process uses several Huffman trees. The more
 *      common source values are represented by shorter bit sequences.
 *
 *      Each code tree is stored in a compressed form which is itself
 * a Huffman encoding of the lengths of all the code strings (in
 * ascending order by source values).  The actual code strings are
 * reconstructed from the lengths in the inflate process, as described
 * in the zlib deflate specification.
 *
 *  REFERENCES
 *
 *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
 *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
 *
 *      Storer, James A.
 *          Data Compression:  Methods and Theory, pp. 49-50.
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
 *
 *      Sedgewick, R.
 *          Algorithms, p290.
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
 */

/* zdelta:
 *
 * modified: 
 *          tr_static_init ()
 *          init_block     ()
 *          build_bl_tree  ()
 *          send_all_trees ()
 *          compress_block ()
 *          _tr_flush_block() -- added prefix zd
 * added:
 *          --
 * removed:
 *          --
 */


/* @(#) $Id$ */

/* #define GEN_TREES_H */

#include "deflate.h"
#include <stdio.h>
#ifdef DEBUG
#  include <ctype.h>
#endif

/* ===========================================================================
 * Constants
 */

#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */

#define END_BLOCK 256
/* end of block literal code */

#define REP_3_6      16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */

#define REPZ_3_10    17
/* repeat a zero length 3-10 times  (3 bits of repeat count) */

#define REPZ_11_138  18
/* repeat a zero length 11-138 times  (7 bits of repeat count) */

/* extra bits for each length code */
local const int extra_lbits[L_CODES] 
   = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,
      5,5,5,5,7,7,8,8,9,9,10,10,0,
      0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,
      5,5,5,5,7,7,8,8,9,9,10,10,0,
      0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,
      5,5,5,5,7,7,8,8,9,9,10,10,0
   };

local const int extra_dbits[DIST_CODES] /* extra bits for each distance code */
   = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};

local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};

local const uch bl_order[BL_CODES]
   = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};

/* The lengths of the bit length codes are sent in order of decreasing
 * probability, to avoid transmitting the lengths for unused bit length codes.
 */


#define Buf_size (8 * 2*sizeof(char))
/* Number of bits used within bi_buf. (bi_buf might be implemented on
 * more than 16 bits on some systems.)
 */

/* ===========================================================================
 * Local data. These are initialized only once.
 */



#if defined(GEN_TREES_H) || !defined(STDC)
/* non ANSI compilers may not accept trees.h */

local ct_data static_ltree[L_CODES];
/* The static lenght trees. Since the bit lengths are imposed, there is no
 * need for the L_CODES extra codes used during heap construction. However
 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
 * below).
 */

local ct_data static_dtree[D_CODES+1];
/* The static literal/distance tree  */

local ct_data static_ztree[Z_CODES];
/* The static zdelta tree */

/* zdelta: added prefix zd */
uch zd_dist_code[DIST_CODE_LEN];
/* Distance codes. The first 256 values correspond to the distances
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
 * the 15 bit distances.
 */

/* zdelta: added prefix zd */
uch zd_length_code[LENGTH_CODE_LEN];
/* length code for each normalized match length (0 == MIN_MATCH) */

local int base_length[LENGTH_CODE_LEN];
/* First normalized length for each code (0 = MIN_MATCH) */

local int base_dist[D_CODES];
/* First normalized distance for each code (0 = distance of 1) */

#else
#  include "trees.h"
#endif /* GEN_TREES_H */

struct static_tree_desc_s {
    const ct_data *static_tree;  /* static tree or NULL */
    const intf *extra_bits;      /* extra bits for each code or NULL */
    int     extra_base;          /* base index for extra_bits */
    int     elems;               /* max number of elements in the tree */
    int     max_length;          /* max bit length for the codes */
};

local static_tree_desc  static_l_desc =
{static_ltree, extra_lbits, 0, L_CODES, MAX_BITS};

local static_tree_desc  static_d_desc =
{static_dtree, extra_dbits, LITERALS+1, D_CODES, MAX_BITS};

local static_tree_desc  static_z_desc =
{static_ztree, NULL, Z_CODES, Z_CODES, MAX_BITS};

local static_tree_desc  static_bl_desc =
{(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};


/* ===========================================================================
 * Local (static) routines in this file.
 */

/* zdelta: modified */
local void tr_static_init OF((void));
local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
local int  build_bl_tree  OF((deflate_state *s));
local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
			      int zdcodes, int blcodes));
local void compress_block OF((deflate_state *s, ct_data *ltree,
                              ct_data *dtree, ct_data *zdtree));

/* zdelta: unchanged from  zlib 1.1.3 */
local void init_block     OF((deflate_state *s));
local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
local void build_tree     OF((deflate_state *s, tree_desc *desc));
/* NOTUSED local void set_data_type  OF((deflate_state *s)); */
local unsigned bi_reverse OF((unsigned value, int length));
local void bi_windup      OF((deflate_state *s));
local void bi_flush       OF((deflate_state *s));
local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
                              int header));

#ifdef GEN_TREES_H
local void zd_gen_trees_header OF((void));
#endif

#ifndef DEBUG
#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
   /* Send a code of the given tree. c and tree must not have side effects */
#else /* DEBUG */
#  define send_code(s, c, tree) \
     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
       send_bits(s, tree[c].Code, tree[c].Len); }
#endif



/* ===========================================================================
 * Output a short LSB first on the stream.
 * IN assertion: there is enough room in pendingBuf.
 */
#define put_short(s, w) { \
    put_byte(s, (uch)((w) & 0xff)); \
    put_byte(s, (uch)((ush)(w) >> 8)); \
}

/* ===========================================================================
 * Send a value on a given number of bits.
 * IN assertion: length <= 16 and value fits in length bits.
 */
#ifdef DEBUG
local void send_bits      OF((deflate_state *s, int value, int length));

local void send_bits(s, value, length)
     deflate_state *s;
     int value;  /* value to send */
     int length; /* number of bits */
{
  Tracevv((stderr," l %2d v %4x ", length, value));
  if(length <= 0 || length > 15)
    printf("length %u\n",length);
  Assert(length > 0 && length <= 15, "invalid length");
  s->bits_sent += (ulg)length;

  /* If not enough room in bi_buf, use (valid) bits from bi_buf and
   * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
   * unused bits in value.
   */
  if (s->bi_valid > (int)Buf_size - length) {
    s->bi_buf |= (value << s->bi_valid);
    put_short(s, s->bi_buf);
    s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
    s->bi_valid += length - Buf_size;
  } else {
    s->bi_buf |= value << s->bi_valid;
    s->bi_valid += length;
  }
}
#else /* !DEBUG */

#define send_bits(s, value, length) \
{ int len = length;\
  if (s->bi_valid > (int)Buf_size - len) {\
    int val = value;\
    s->bi_buf |= (val << s->bi_valid);\
    put_short(s, s->bi_buf);\
    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
    s->bi_valid += len - Buf_size;\
  } else {\
    s->bi_buf |= (value) << s->bi_valid;\
    s->bi_valid += len;\
  }\
}
#endif /* DEBUG */


#define MAX(a,b) (a >= b ? a : b)
/* the arguments must not have side effects */

/* ===========================================================================
 * Initialize the various 'constant' tables.
 * zdelta: modified
 */
local void tr_static_init()
{
#if defined(GEN_TREES_H) || !defined(STDC)
  static int static_init_done = 0;
  int n;        /* iterates over tree elements */
  int bits;     /* bit counter */
  int length;   /* length value */
  int code;     /* code value */
  int dist;     /* distance index */
  ush bl_count[MAX_BITS+1];
  /* number of codes at each bit length for an optimal tree */

  if (static_init_done) return;
  
  /* For some embedded targets, global variables are not initialized: */
  static_l_desc.static_tree  = static_ltree;
  static_l_desc.extra_bits   = extra_lbits;
  static_d_desc.static_tree  = static_dtree;
  static_d_desc.extra_bits   = extra_dbits;
  static_z_desc.static_tree  = static_ztree; /* zdelta: additional tree */ 
  static_z_desc.extra_bits   = NULL; 
  static_bl_desc.extra_bits  = extra_blbits;
  
  /* Initialize the mapping length (0..4096) -> length code (0..44) */
  length = 0;
  for (code = 0; code < 28; code++) {
    base_length[code] = length;
    for (n = 0; n < (1<<extra_lbits[code]); n++) {
      zd_length_code[length++] = (uch)code;
    }
  }
  Assert (length == 256, "tr_static_init: length != 256");
  length >>= 6; /* from now on, all lengths are divided by 64 */
  for ( ; code < LENGTH_CODES-1; code++) {
    base_length[code] = length << 6;
    for (n = 0; n < (1<<(extra_lbits[code]-6)); n++) {
      zd_length_code[256+length++] = (uch)code;
    }
  }
  /* overwrite code 36, that is the code for MAX_MATCH */
  base_length[code] = (length<<6) - 1;
  zd_length_code[256+length] = (uch) code;

  Assert (256+length == 320, "tr_static_init: 256+length != 320");
  /* Note that the length 4095 (match length 4098) can be represented
   * in two different ways: codes 35 + 10 bits or code 36, so we
   * overwrite length_code[36] to use the best encoding:
   */
  
  /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
  dist = 0;
  for (code = 0 ; code < 16; code++) {
    base_dist[code] = dist;
    for (n = 0; n < (1<<extra_dbits[code]); n++) {
      zd_dist_code[dist++] = (uch)code;
    }
  }
  Assert (dist == 256, "tr_static_init: dist != 256");
  dist >>= 7; /* from now on, all distances are divided by 128 */
  for ( ; code < DIST_CODES; code++) {
    base_dist[code] = dist << 7;
    for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
      zd_dist_code[256 + dist++] = (uch)code;
    }
  }
  Assert (dist == 256, "tr_static_init: 256+dist != 512");

  /* Construct the codes of the static length tree */
  for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
  n = 0;
  while (n <= 6)   static_ltree[n++].Len = 5, bl_count[5]++;
  while (n <= 7)   static_ltree[n++].Len = 6, bl_count[6]++;
  while (n <= 9)   static_ltree[n++].Len = 5, bl_count[5]++;
  while (n <= 13)  static_ltree[n++].Len = 6, bl_count[6]++;
  while (n <= 14)  static_ltree[n++].Len = 7, bl_count[7]++;
  while (n <= 15)  static_ltree[n++].Len = 9, bl_count[9]++;
  while (n <= 16)  static_ltree[n++].Len = 7, bl_count[7]++;
  while (n <= 36)  static_ltree[n++].Len = 9, bl_count[9]++;
  while (n <= 37)  static_ltree[n++].Len = 6, bl_count[6]++;
  while (n <= 40)  static_ltree[n++].Len = 5, bl_count[5]++;
  while (n <= 45)  static_ltree[n++].Len = 6, bl_count[6]++;
  while (n <= 47)  static_ltree[n++].Len = 7, bl_count[7]++;
  while (n <= 48)  static_ltree[n++].Len = 9, bl_count[9]++;
  while (n <= 49)  static_ltree[n++].Len = 7, bl_count[7]++;
  while (n <= 73)  static_ltree[n++].Len = 9, bl_count[9]++;
  while (n <= 78)  static_ltree[n++].Len = 5, bl_count[5]++;
  while (n <= 83)  static_ltree[n++].Len = 6, bl_count[6]++;
  while (n <= 87)  static_ltree[n++].Len = 7, bl_count[7]++;
  while (n <= 89)  static_ltree[n++].Len = 9, bl_count[9]++;
  while (n <= 91)  static_ltree[n++].Len = 7, bl_count[7]++;
  while (n <= 93)  static_ltree[n++].Len = 9, bl_count[9]++;  
  while (n <= 94)  static_ltree[n++].Len = 8, bl_count[8]++;
  while (n <= 110) static_ltree[n++].Len = 9, bl_count[9]++;  
  
  gen_codes((ct_data *)static_ltree, L_CODES-1, bl_count);

  /* Construct the codes of the  static literal/distance tree */
  for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
  n = 0;
  while (n <= 254) static_dtree[n++].Len = 9, bl_count[9]++;
  while (n <= 286) static_dtree[n++].Len = 6, bl_count[6]++;
  while (n <= 287) static_dtree[n++].Len = 9, bl_count[9]++;

  gen_codes((ct_data *)static_dtree, D_CODES, bl_count);

  /* Construct the codes of the  static zdelta tree */
  for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
  n = 0;
  while (n <= 1) static_ztree[n++].Len = 2, bl_count[2]++;
  while (n <= 3) static_ztree[n++].Len = 3, bl_count[3]++;
  while (n <= 7) static_ztree[n++].Len = 4, bl_count[4]++;

  gen_codes((ct_data *)static_ztree, Z_CODES-1, bl_count);

  static_init_done = 1;

#  ifdef GEN_TREES_H
  zd_gen_trees_header();
#  endif
#endif /* defined(GEN_TREES_H) || !defined(STDC) */
}

/* ===========================================================================
 * Genererate the file trees.h describing the static trees.
 * zdelta: modified
 */
#ifdef GEN_TREES_H
#  ifndef DEBUG
#    include <stdio.h>
#  endif

#  define SEPARATOR(i, last, width) \
      ((i) == (last)? "\n};\n\n" :    \
       ((i) % (width) == (width)-1 ? ",\n" : ", "))

void zd_gen_trees_header()
{
  FILE *header = fopen("trees.h", "w");
  int i;

  Assert (header != NULL, "Can't open trees.h");
  fprintf(header,
	  "/* header created automatically with -DGEN_TREES_H */\n\n");

  fprintf(header, "local const ct_data static_ltree[L_CODES] = {\n");
  for (i = 0; i < L_CODES; i++) {
    fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
	    static_ltree[i].Len, SEPARATOR(i, L_CODES-1, 5));
  }

  fprintf(header, "local const ct_data static_dtree[D_CODES+1] = {\n");
  for (i = 0; i < D_CODES+1; i++) {
    fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
	    static_dtree[i].Len, SEPARATOR(i, D_CODES, 5));
  }


  fprintf(header,"#if REFNUM > 1\n");
  fprintf(header, "local const ct_data static_ztree[Z_CODES] = {\n");
  for (i = 0; i < Z_CODES; i++) {
    fprintf(header, "{{%2u},{%2u}}%s", static_ztree[i].Code,
	    static_ztree[i].Len, SEPARATOR(i, Z_CODES-1, 5));
  }
  fprintf(header,"#else\n");
  fprintf(header,"local const ct_data static_ztree[Z_CODES] = {\n");
  fprintf(header,"{{ 0},{ 1}}, {{ 1},{ 1}}\n};\n");
  fprintf(header,"#endif\n\n");  

  fprintf(header, "const uch zd_dist_code[DIST_CODE_LEN] = {\n");
  for (i = 0; i < DIST_CODE_LEN; i++) {
    fprintf(header, "%2u%s", zd_dist_code[i],
	    SEPARATOR(i, DIST_CODE_LEN-1, 20));
  }
  
  fprintf(header, "const uch zd_length_code[LENGTH_CODE_LEN]= {\n");
  for (i = 0; i < LENGTH_CODE_LEN; i++) {
    fprintf(header, "%2u%s", zd_length_code[i],
	    SEPARATOR(i, LENGTH_CODE_LEN-1, 20));
  }

  fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
  for (i = 0; i < LENGTH_CODES; i++) {
    fprintf(header, "%1u%s", base_length[i],
	    SEPARATOR(i, LENGTH_CODES-1, 10));
  }

  fprintf(header, "local const int base_dist[DIST_CODES] = {\n");
  for (i = 0; i < DIST_CODES; i++) {
    fprintf(header, "%5u%s", base_dist[i],
	    SEPARATOR(i, DIST_CODES-1, 10));
  }
  
  fclose(header);
}
#endif /* GEN_TREES_H */

/* ===========================================================================
 * Initialize the tree data structures for a new zlib stream.
 * zdelta: modified
 *         added prefix zd 
 */
void zd_tr_init(s)
    deflate_state *s;
{
  tr_static_init();

  s->l_desc.dyn_tree  = s->dyn_ltree;
  s->l_desc.stat_desc = &static_l_desc;
  
  s->d_desc.dyn_tree  = s->dyn_dtree;
  s->d_desc.stat_desc = &static_d_desc;
  
  s->z_desc.dyn_tree  = s->dyn_ztree;
  s->z_desc.stat_desc = &static_z_desc;
  /* zdelta: initialize additional trees */
  
  s->bl_desc.dyn_tree  = s->bl_tree;
  s->bl_desc.stat_desc = &static_bl_desc;
  
  s->bi_buf = 0;
  s->bi_valid = 0;
  s->last_eob_len = 8; /* enough lookahead for inflate */
  
#ifdef DEBUG
  s->compressed_len = 0L;
  s->bits_sent      = 0L;
#endif

  /* Initialize the first block of the first file: */
  init_block(s);
}

/* ===========================================================================
 * Initialize a new block.
 * zdelta: modified
 */
local void init_block(s)
    deflate_state *s;
{
  int n; /* iterates over tree elements */

  /* Initialize the trees. */    
  for (n = 0; n < L_CODES;  n++)  s->dyn_ltree[n].Freq  = 0;
  for (n = 0; n < D_CODES;  n++)  s->dyn_dtree[n].Freq  = 0;
  for (n = 0; n < Z_CODES; n++)  s->dyn_ztree[n].Freq  = 0; /* zdelta */
  for (n = 0; n < BL_CODES; n++)  s->bl_tree[n].Freq    = 0;
    
  s->dyn_dtree[END_BLOCK].Freq = 1;
  s->opt_len = s->static_len = 0L;
  s->last_lit = s->matches = 0;
}

#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */


/* ===========================================================================
 * Remove the smallest element from the heap and recreate the heap with
 * one less element. Updates heap and heap_len.
 */
#define pqremove(s, tree, top) \
{\
    top = s->heap[SMALLEST]; \
    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
    pqdownheap(s, tree, SMALLEST); \
}

/* ===========================================================================
 * Compares to subtrees, using the tree depth as tie breaker when
 * the subtrees have equal frequency. This minimizes the worst case length.
 */
#define smaller(tree, n, m, depth) \
   (tree[n].Freq < tree[m].Freq || \
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))

/* ===========================================================================
 * Restore the heap property by moving down the tree starting at node k,
 * exchanging a node with the smallest of its two sons if necessary, stopping
 * when the heap property is re-established (each father smaller than its
 * two sons).
 */
local void pqdownheap(s, tree, k)
    deflate_state *s;
    ct_data *tree;  /* the tree to restore */
    int k;               /* node to move down */
{
  int v = s->heap[k];
  int j = k << 1;  /* left son of k */
  while (j <= s->heap_len) {
    /* Set j to the smallest of the two sons: */
    if (j < s->heap_len &&
	smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
      j++;
    }
    /* Exit if v is smaller than both sons */
    if (smaller(tree, v, s->heap[j], s->depth)) break;
    
    /* Exchange v with the smallest son */
    s->heap[k] = s->heap[j];  k = j;
    
    /* And continue down the tree, setting j to the left son of k */
    j <<= 1;
  }
  s->heap[k] = v;
}

/* ===========================================================================
 * Compute the optimal bit lengths for a tree and update the total bit length
 * for the current block.
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
 *    above are the tree nodes sorted by increasing frequency.
 * OUT assertions: the field len is set to the optimal bit length, the
 *     array bl_count contains the frequencies for each bit length.
 *     The length opt_len is updated; static_len is also updated if stree is
 *     not null.
 */
local void gen_bitlen(s, desc)
    deflate_state *s;
    tree_desc *desc;    /* the tree descriptor */
{
  ct_data *tree        = desc->dyn_tree;
  int max_code         = desc->max_code;
  const ct_data *stree = desc->stat_desc->static_tree;
  const intf *extra    = desc->stat_desc->extra_bits;
  int base             = desc->stat_desc->extra_base;
  int max_length       = desc->stat_desc->max_length;
  int h;              /* heap index */
  int n, m;           /* iterate over the tree elements */
  int bits;           /* bit length */
  int xbits;          /* extra bits */
  ush f;              /* frequency  */
  int overflow = 0;   /* number of elements with bit length too large */

  for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;

  /* In a first pass, compute the optimal bit lengths (which may
   * overflow in the case of the bit length tree).
   */
  tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
  
  for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
    n = s->heap[h];
    bits = tree[tree[n].Dad].Len + 1;
 
    if (bits > max_length) bits = max_length, overflow++;

    tree[n].Len = (ush)bits;
    /* We overwrite tree[n].Dad which is no longer needed */

    if (n > max_code) continue; /* not a leaf node */

    s->bl_count[bits]++;
    xbits = 0;
    if (n >= base) xbits = extra[n-base];
    f = tree[n].Freq;
    s->opt_len += (ulg)f * (bits + xbits);
    if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
  }
  if (overflow == 0) return;

  Trace((stderr,"\nbit length overflow\n"));
  /* This happens for example on obj2 and pic of the Calgary corpus */

  /* Find the first bit length which could increase: */
  do {
    bits = max_length-1;
    while (s->bl_count[bits] == 0) bits--;
    s->bl_count[bits]--;      /* move one leaf down the tree */
    s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
    s->bl_count[max_length]--;
    /* The brother of the overflow item also moves one step up,
     * but this does not affect bl_count[max_length]
     */
    overflow -= 2;
  } while (overflow > 0);

  /* Now recompute all bit lengths, scanning in increasing frequency.
   * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
   * lengths instead of fixing only the wrong ones. This idea is taken
   * from 'ar' written by Haruhiko Okumura.)
   */
  for (bits = max_length; bits != 0; bits--) {
    n = s->bl_count[bits];
    while (n != 0) {
      m = s->heap[--h];
      if (m > max_code) continue;
      if (tree[m].Len != (unsigned) bits) {
	Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
	s->opt_len += ((long)bits - (long)tree[m].Len)
	  *(long)tree[m].Freq;
	tree[m].Len = (ush)bits;
      }
      n--;
    }
  }
}

/* ===========================================================================
 * Generate the codes for a given tree and bit counts (which need not be
 * optimal).
 * IN assertion: the array bl_count contains the bit length statistics for
 * the given tree and the field len is set for all tree elements.
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
local void gen_codes (tree, max_code, bl_count)
     ct_data *tree;             /* the tree to decorate */
     int max_code;              /* largest code with non zero frequency */
     ushf *bl_count;            /* number of codes at each bit length */
{
  ush next_code[MAX_BITS+1]; /* next code value for each bit length */
  ush code = 0;              /* running code value */
  int bits;                  /* bit index */
  int n;                     /* code index */
  
  /* The distribution counts are first used to generate the code values
   * without bit reversal.
   */
  for (bits = 1; bits <= MAX_BITS; bits++) {
    next_code[bits] = code = (code + bl_count[bits-1]) << 1;
  }
  /* Check that the bit counts in bl_count are consistent. The last code
   * must be all ones.
   */
  Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
	  "inconsistent bit counts");
  Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

  for (n = 0;  n <= max_code; n++) {
    int len = tree[n].Len;
    if (len == 0) continue;
    /* Now reverse the bits */
    tree[n].Code = bi_reverse(next_code[len]++, len);
    
    Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",\
				   n, (isgraph(n) ? n : ' '), len, \
				   tree[n].Code, next_code[len]-1));
  }
}

/* ===========================================================================
 * Construct one Huffman tree and assigns the code bit strings and lengths.
 * Update the total bit length for the current block.
 * IN assertion: the field freq is set for all tree elements.
 * OUT assertions: the fields len and code are set to the optimal bit length
 *     and corresponding code. The length opt_len is updated; static_len is
 *     also updated if stree is not null. The field max_code is set.
 */
local void build_tree(s, desc)
     deflate_state *s;
     tree_desc *desc; /* the tree descriptor */
{
  ct_data *tree         = desc->dyn_tree;
  const ct_data *stree  = desc->stat_desc->static_tree;
  int elems             = desc->stat_desc->elems;
  int n, m;          /* iterate over heap elements */
  int max_code = -1; /* largest code with non zero frequency */
  int node;          /* new node being created */

  /* Construct the initial heap, with least frequent element in
   * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
   * heap[0] is not used.
   */
  s->heap_len = 0, s->heap_max = HEAP_SIZE;

  for (n = 0; n < elems; n++) {
    if (tree[n].Freq != 0) {
      s->heap[++(s->heap_len)] = max_code = n;
      s->depth[n] = 0;
    } else {
      tree[n].Len = 0;
    }
  }

  /* The pkzip format requires that at least one distance code exists,
   * and that at least one bit should be sent even if there is only one
   * possible code. So to avoid special checks later on we force at least
   * two codes of non zero frequency.
   */
  while (s->heap_len < 2) {
    node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
    tree[node].Freq = 1;
    s->depth[node] = 0;
    s->opt_len--; if (stree) s->static_len -= stree[node].Len;
    /* node is 0 or 1 so it does not have extra bits */
  }
  desc->max_code = max_code;
  
  /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
   * establish sub-heaps of increasing lengths:
   */
  for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);

  /* Construct the Huffman tree by repeatedly combining the least two
   * frequent nodes.
   */
  node = elems;              /* next internal node of the tree */
  do {
    pqremove(s, tree, n);  /* n = node of least frequency */
    m = s->heap[SMALLEST]; /* m = node of next least frequency */
    
    s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
    s->heap[--(s->heap_max)] = m;
    
    /* Create a new node father of n and m */
    tree[node].Freq = tree[n].Freq + tree[m].Freq;
    s->depth[node] = (uch) (MAX(s->depth[n], s->depth[m]) + 1);
    tree[n].Dad = tree[m].Dad = (ush)node;
#ifdef DUMP_BL_TREE 
    if (tree == s->bl_tree) {
      fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
	      node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
    }
#endif
    /* and insert the new node in the heap */
    s->heap[SMALLEST] = node++;
    pqdownheap(s, tree, SMALLEST);
    
  } while (s->heap_len >= 2);
  
  s->heap[--(s->heap_max)] = s->heap[SMALLEST];
  
  /* At this point, the fields freq and dad are set. We can now
   * generate the bit lengths.
   */
  gen_bitlen(s, (tree_desc *)desc);
  
  /* The field len is now set, we can generate the bit codes */
  gen_codes ((ct_data *)tree, max_code, s->bl_count);
}

/* ===========================================================================
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree.
 */
local void scan_tree (s, tree, max_code)
     deflate_state *s;
     ct_data *tree;   /* the tree to be scanned */
     int max_code;    /* and its largest code of non zero frequency */
{
  int n;                     /* iterates over all tree elements  */
  int prevlen = -1;          /* last emitted length              */
  int curlen;                /* length of current code           */
  int nextlen = tree[0].Len; /* length of next code              */
  int count = 0;             /* repeat count of the current code */
  int max_count = 7;         /* max repeat count                 */
  int min_count = 4;         /* min repeat count                 */
    
  if (nextlen == 0) max_count = 138, min_count = 3;
  tree[max_code+1].Len = (ush)0xffff; /* guard */

  for (n = 0; n <= max_code; n++) {
    curlen = nextlen; nextlen = tree[n+1].Len;
    if (++count < max_count && curlen == nextlen) {
      continue;
    } else if (count < min_count) {
      s->bl_tree[curlen].Freq += count;
    } else if (curlen != 0) {
      if (curlen != prevlen) s->bl_tree[curlen].Freq++;
      s->bl_tree[REP_3_6].Freq++;
    } else if (count <= 10) {
      s->bl_tree[REPZ_3_10].Freq++;
    } else {
      s->bl_tree[REPZ_11_138].Freq++;
    }
    count = 0; prevlen = curlen;
    if (nextlen == 0) {
      max_count = 138, min_count = 3;
    } else if (curlen == nextlen) {
      max_count = 6, min_count = 3;
    } else {
      max_count = 7, min_count = 4;
    }
  }
}

/* ===========================================================================
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
local void send_tree (s, tree, max_code)
     deflate_state *s;
     ct_data *tree; /* the tree to be scanned */
     int max_code;       /* and its largest code of non zero frequency */
{
  int n;                     /* iterates over all tree elements */
  int prevlen = -1;          /* last emitted length */
  int curlen;                /* length of current code */
  int nextlen = tree[0].Len; /* length of next code */
  int count = 0;             /* repeat count of the current code */
  int max_count = 7;         /* max repeat count */
  int min_count = 4;         /* min repeat count */

  /* tree[max_code+1].Len = -1; */  /* guard already set */
  if (nextlen == 0) max_count = 138, min_count = 3;

  for (n = 0; n <= max_code; n++) {
    Tracevv((stderr, "code: %3u len: %3u\n", n, tree[n].Len));
    curlen = nextlen; nextlen = tree[n+1].Len;
    if (++count < max_count && curlen == nextlen) {
      continue;
    } else if (count < min_count) {
      do { send_code(s, curlen, s->bl_tree); 
      } while (--count != 0);
      
    } else if (curlen != 0) {
      if (curlen != prevlen) {
	send_code(s, curlen, s->bl_tree); count--; 
      }
      Assert(count >= 3 && count <= 6, " 3_6?");
      send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
    } else if (count <= 10) {
      send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
    } else {
      send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
    }

    count = 0; prevlen = curlen;
    if (nextlen == 0) {
      max_count = 138, min_count = 3;
    } else if (curlen == nextlen) {
      max_count = 6, min_count = 3;
    } else {
      max_count = 7, min_count = 4;
    }
  }
}

/* ===========================================================================
 * Construct the Huffman tree for the bit lengths and return the index in
 * bl_order of the last bit length code to send.
 * zdelta: modified
 */
local int build_bl_tree(s)
    deflate_state *s;
{
  int max_blindex;  /* index of last bit length code of non zero freq */
  
  /* Determine the bit length frequencies for literal and distance trees */
  scan_tree(s, (ct_data *)s->dyn_ltree,  s->l_desc.max_code);
  scan_tree(s, (ct_data *)s->dyn_dtree,  s->d_desc.max_code);
#if REFNUM>1
  scan_tree(s, (ct_data *)s->dyn_ztree,  s->z_desc.max_code); /* zdelta */
#endif
  /* opt_len now includes the length of the tree representations, except
   * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
   */

  /* Build the bit length tree: */
  build_tree(s, (tree_desc *)(&(s->bl_desc)));

  /* Determine the number of bit length codes to send. The pkzip format
   * requires that at least 4 bit length codes be sent. (appnote.txt says
   * 3 but the actual value used is 4.)
   */
  for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
    if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
  }
  /* Update opt_len to include the bit length tree and counts */
#if REFNUM>1
  s->opt_len += 3*(max_blindex+1) +7+5+3+4; /* zdelta */
#else
  s->opt_len += 3*(max_blindex+1) +7+5+4; /* zdelta */
#endif

  Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
	  s->opt_len, s->static_len));
  
  return max_blindex;
}

/* ===========================================================================
 * Send the header for a block using dynamic Huffman trees: the counts, the
 * lengths of the bit length codes, the literal tree and the distance tree.
 * IN assertion: lcodes >= 257, dcodes >= 1, zdcodes >=1, blcodes >= 4.
 * zdelta: modified
 */
local void send_all_trees(s, lcodes, dcodes, zcodes, blcodes)
     deflate_state *s;
     int lcodes, dcodes, zcodes, blcodes; /* number of codes for each tree */
{
  int rank;                    /* index in bl_order */

  Assert (lcodes >= 1 && dcodes >= 257 && blcodes >= 4 && zcodes>=1,
	  "not enough codes");
  Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES &&
	  zcodes <= Z_CODES, "too many codes");

  send_bits(s, lcodes-1,   7); /* not +255 as stated in appnote.txt */
  Tracev((stderr, "\n # len codes   :%u", lcodes-1));

  send_bits(s, dcodes-257, 5);
  Tracev((stderr, "\n # dist codes  :%u", dcodes-257));

#if REFNUM>1
  send_bits(s, zcodes-1,   3); /* zdelta code tree size */
  Tracev((stderr, "\n # zdelta codes:%u", zcodes-1));
#endif

  send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
  Tracev((stderr, "\n # bl codes    :%u", blcodes-4));

  Tracev((stderr, "\nbl counts: "));
    for (rank = 0; rank < blcodes; rank++) {
      Tracev((stderr, "\nbl code %2d len %2d", 
	      bl_order[rank], s->bl_tree[bl_order[rank]].Len));
      send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
    }
  Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));

  send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
  Tracev((stderr, "\nlen tree: sent %ld", s->bits_sent));
  
  send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
  Tracev((stderr, "\nlit/dist tree: sent %ld", s->bits_sent));

#if REFNUM > 1
  send_tree(s, (ct_data *)s->dyn_ztree, zcodes-1); /* zdelta code tree */
  Tracev((stderr, "\nzd tree: sent %ld", s->bits_sent));
#endif
}

/* ===========================================================================
 * Send a stored block
 * zdelta: modified
 *         added prefix zd 
 */
void zd_tr_stored_block(s, buf, stored_len, eof)
     deflate_state *s;
     charf *buf;       /* input block */
     ulg stored_len;   /* length of input block */
     int eof;          /* true if this is the last block for a file */
{
  send_bits(s, (STORED_BLOCK<<1)+eof, 3);  /* send block type */
#ifdef DEBUG
  s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
  s->compressed_len += (stored_len + 4) << 3;
#endif
  copy_block(s, buf, (unsigned)stored_len, 1); /* with header */


  /* zdelta: restore the pointers in the reference window
   * currently there is no explicity mechanism to way to provide the 
   * decompressor with the positions of these pointers; 
   * when a non-empty store block is emitted, we should restore the pointer
   * states before the start of that block - that is where the decompressor
   * will expect them to be!
   */
  if(stored_len){ 
    s->rwptr[0]  = s->rwptr_save[0];
    s->rwptr[1]  = s->rwptr_save[1];
    s->stable[0] = s->stable_save[0];
    s->stable[1] = s->stable_save[1];
  }
}
/* ===========================================================================
 * Send one empty static block to give enough lookahead for inflate.
 * This takes 9 bits, of which 7 may remain in the bit buffer.
 * The current inflate code requires 9 bits of lookahead. If the
 * last two codes for the previous block (real code plus EOB) were coded
 * on 5 bits or less, inflate may have only 5+2 bits of lookahead to decode
 * the last real code. In this case we send two empty static blocks instead
 * of one. (There are no problems if the previous block is stored or fixed.)
 * To simplify the code, we assume the worst case of last real code encoded
 * on one bit only.
 *
 * zdelta: added prefix zd 
 */
void zd_tr_align(s)
     deflate_state *s;
{
  send_bits(s, STATIC_TREES<<1, 3);
  send_code(s, END_BLOCK, static_dtree);
#ifdef DEBUG
  s->compressed_len += 9L; /* 3 for block type, 6 for EOB */
#endif
  bi_flush(s);
  /* Of the 9 bits for the empty block, we have already sent
   * (9 - bi_valid) bits. The lookahead for the last real code (before
   * the EOB of the previous block) was thus at least one plus the length
   * of the EOB plus what we have just sent of the empty static block.
   */
  if (1 + s->last_eob_len + 9 - s->bi_valid < 9) {
    send_bits(s, STATIC_TREES<<1, 3);
    send_code(s, END_BLOCK, static_dtree);
#ifdef DEBUG
    s->compressed_len += 9L;
#endif
    bi_flush(s);
  }
  s->last_eob_len = 6;
}

/* ===========================================================================
 * Determine the best encoding for the current block: dynamic trees, static
 * trees or store, and output the encoded block to the zip file.
 * zdelta: modified
 *         added prefix zd 
 */
void zd_tr_flush_block(s, buf, stored_len, eof)
    deflate_state *s;
    charf *buf;       /* input block, or NULL if too old */
    ulg stored_len;   /* length of input block */
    int eof;          /* true if this is the last block for a file */
{
  ulg opt_lenb = 0, static_lenb = 0; /* opt_len and static_len in bytes */
  int max_blindex = 0;  /* index of last bit length code of non zero freq */
  int refnum = s->strm->refnum;
  int i;
  uch stored_allowed = 1;

  /*  ulg temp_opt = 0, temp_stat = 0;  dim: statistics */
  /* Build the Huffman trees unless a stored block is forced */
  if (s->level > 0) {
    /* Check if the file is ascii or binary */
    /* (s->data_type == Z_UNKNOWN) set_data_type(s); */

    /* Construct the length trees */
    build_tree(s, (tree_desc *)(&(s->l_desc)));
    Tracev((stderr, "\nlen data: dyn %ld, stat %ld", s->opt_len,
	    s->static_len));

    /* Construct the literal and distance trees */
    build_tree(s, (tree_desc *)(&(s->d_desc)));
    Tracev((stderr, "\nlit/dist data: dyn %ld, stat %ld", s->opt_len,
	    s->static_len));

#if REFNUM>1
    build_tree(s, (tree_desc *)(&(s->z_desc)));
#endif
    /* Build the bit length tree for the above tree trees, and get the index
     * in bl_order of the last bit length code to send.
     */
    max_blindex = build_bl_tree(s);

    /* Determine the best encoding. Compute first the block length in bytes*/
    opt_lenb = (s->opt_len+3+7)>>3;
    static_lenb = (s->static_len+3+7)>>3;
    if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
    
  } else {
    Assert(buf != (char*)0, "lost buf");
    opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
  }

#ifdef FORCE_STORED
  if (buf != (char*)0) { /* force stored block */
#else

  for(i=0; i<refnum; i++){
    stored_allowed &= s->stored_allowed[i];
  } 

  if (stored_allowed && stored_len+4 <= opt_lenb && buf != (char*)0){ 
    /* 4: two words for the lengths */
    /* zdelta: s->stored_allowed is false if the reference window is
     * slided; this invalidates the stored reference window pointers
     * and the decompressor will be confused if a stored block is emitted
     */
#endif
    /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
     * Otherwise we can't have processed more than WSIZE input bytes since
     * the last block flush, because compression would have been
     * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
     * transform a block into a stored block.
     */
    zd_tr_stored_block(s, buf, stored_len, eof);

#ifdef FORCE_STATIC
  } else if (static_lenb >= 0) { /* force static trees */
#else
  } else if (static_lenb == opt_lenb) {
#endif
    send_bits(s, (STATIC_TREES<<1)+eof, 3);
    compress_block(s, (ct_data*)static_ltree, (ct_data*)static_dtree, 
		   (ct_data*)static_ztree);
#ifdef DEBUG
    s->compressed_len += 3 + s->static_len;
#endif
  } else {
    send_bits(s, (DYN_TREES<<1)+eof, 3);
    send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,\
		   s->z_desc.max_code+1,max_blindex+1);
#if REFNUM>1
    compress_block(s, (ct_data*)s->dyn_ltree, (ct_data*)s->dyn_dtree,
		   (ct_data*)s->dyn_ztree);
#else
    compress_block(s, (ct_data*)s->dyn_ltree, (ct_data*)s->dyn_dtree,
		   (ct_data*)static_ztree);
#endif
#ifdef DEBUG
    s->compressed_len += 3 + s->opt_len;
#endif
  }

#if REFNUM>1
  Assert (s->compressed_len == s->bits_sent, "bad compressed size");
  /* The above check is made mod 2^32, for files larger than 512 MB
   * and uLong implemented on 32 bits.
   */
#endif
  init_block(s);

  /* zdelta: needed to handle correctly the stored blocks */
  for(i=0; i<refnum*2; ++i){ 
    s->rwptr_save[i]  = s->rwptr[i];
    s->stable_save[i] = s->stable[i];
  }
  for(i=0; i<refnum; ++i){ s->stored_allowed[i]=1; }

  if (eof) {
    /* provide enough lookahead for inflate 
     * the current lookahead bits required for distance codes (which contain
     * the END_BLOCK code) is 9 (see inffixed.h fixed_bd).
     */
    if( s->noheader && (16-s->bi_valid)%8+s->last_eob_len%9<9 ){
      bi_windup(s);
      put_byte(s, 0); 
    }
    else{
      bi_windup(s);
    }
#ifdef DEBUG
    s->compressed_len += 7;  /* align on byte boundary */
#endif
  }
  Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
	  s->compressed_len-7*eof));
}

/* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 * zdelta: added prefix zd 
 */ 
#ifdef NOTUSED
int zd_tr_tally (s, dist, lc)
     deflate_state *s;
     unsigned dist; /* distance of matched string */
     unsigned lc;   /* match length-MIN_MATCH or unmatched char (if dist==0) */
{
  s->d_buf[s->last_lit] = (ush)dist;
  s->l_buf[s->last_lit++] = (uch)lc;
  if (dist == 0) {
    /* lc is the unmatched char */
    s->dyn_ltree[lc].Freq++;
  } else {
    s->matches++;
    /* Here, lc is the match length - MIN_MATCH */
    dist--;             /* dist = match distance - 1 */
    Assert((ush)dist < (ush)MAX_DIST(s) &&
	   (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
	   (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
    
    s->dyn_ltree[zd_length_code[lc]+LITERALS+1].Freq++;
    s->dyn_dtree[d_code(dist)].Freq++;
  }

#ifdef TRUNCATE_BLOCK
  /* Try to guess if it is profitable to stop the current block here */
  if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
    /* Compute an upper bound for the compressed length */
    ulg out_length = (ulg)s->last_lit*8L;
    ulg in_length = (ulg)((long)s->strstart - s->block_start);
    int dcode;
    for (dcode = 0; dcode < D_CODES; dcode++) {
      out_length += (ulg)s->dyn_dtree[dcode].Freq *
	(5L+extra_dbits[dcode]);
    }
    out_length >>= 3;
    Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
	    s->last_lit, in_length, out_length,
	    100L - out_length*100L/in_length));
    if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
  }
#endif
  return (s->last_lit == s->lit_bufsize-1);
  /* We avoid equality with lit_bufsize because of wraparound at 64K
   * on 16 bit machines and because stored blocks are restricted to
   * 64K-1 bytes.
   */
}
#endif

/* ===========================================================================
 * Send the block data compressed using the given Huffman trees
 * zdelta: modified
 */
local void compress_block(s, ltree, dtree, zdtree)
    deflate_state *s;
    ct_data *ltree;  /* literal tree      */
    ct_data *dtree;  /* distance tree     */
    ct_data *zdtree; /* zdelta code tree  */
{
  unsigned dist;      /* distance of matched string */
  int lc;             /* match length or unmatched char (if dist == 0) */
  unsigned lx = 0;    /* running index in l_buf */
  unsigned code;      /* the code to send */
  int extra;          /* number of extra bits to send */

  unsigned zd;        /* zdelta pointer */
  
  if (s->last_lit != 0) do {
    zd   = s->z_buf[lx];
    dist = s->d_buf[lx];
    lc   = s->l_buf[lx++];
    if (zd == LITERAL) {
      send_code(s, dist, dtree); /* send a literal byte */
      TraceHuf( (stderr, "d:%u\n", dist) );
      Tracecv(isgraph(dist), (stderr," '%c' ", dist));
    } else {
      /* Here dist is the match distance */
      code = d_code(dist);
      Assert (code < D_CODES, "bad d_code");      
      send_code(s, LITERALS+1+code, dtree);       /* send the distance code */
      extra = extra_dbits[code];
      if (extra != 0) {
	dist -= base_dist[code];
	send_bits(s, dist, extra);          /* send the extra distance bits */
      }
      code = l_code(lc);        /* Here, lc is the match length - MIN_MATCH */
      extra = extra_lbits[code];
      if(zd == TARGET){                             /* target copy          */
	send_code(s, code, ltree);                  /* send the length code */ 
	if (extra != 0) {
	  lc -= base_length[code];
	  send_bits(s, lc, extra);            /* send the extra length bits */
	}
      }
      else{                                         /* reference copy       */
	send_code(s,code+OFFSET(zd),ltree);         /* send the length code */ 
         if (extra != 0) {
	  lc -= base_length[code];
	  send_bits(s, lc, extra);             /* send the extra length bits */
	}
	Assert ((zd & 0x1f) < Z_CODES, "bad zd_code");
	send_code(s, zd & 0x1f, zdtree);                 /* send zdelta code */
	TraceHuf( (stderr, "z:%u\n", zd) );
      }
    }

    /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
    Assert(((unsigned)s->pending) < s->lit_bufsize + 2*lx, 
	   "pendingBuf overflow");
  } while (lx < s->last_lit);

  send_code(s, END_BLOCK, dtree);
  s->last_eob_len = dtree[END_BLOCK].Len;
}


#ifdef NOTUSED
/* ===========================================================================
 * Set the data type to ASCII or BINARY, using a crude approximation:
 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
 * IN assertion: the fields freq of dyn_ltree are set and the total of all
 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
 */
local void set_data_type(s)
     deflate_state *s;
{
  int n = 0;
  unsigned ascii_freq = 0;
  unsigned bin_freq = 0;
  while (n < 7)        bin_freq += s->dyn_dtree[n++].Freq;
  while (n < 128)    ascii_freq += s->dyn_dtree[n++].Freq;
  while (n < LITERALS) bin_freq += s->dyn_dtree[n++].Freq;
  s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII);
}
#endif

/* ===========================================================================
 * Reverse the first len bits of a code, using straightforward code (a faster
 * method would use a table)
 * IN assertion: 1 <= len <= 15
 */
local unsigned bi_reverse(code, len)
     unsigned code; /* the value to invert */
     int len;       /* its bit length */
{
  register unsigned res = 0;
  do {
    res |= code & 1;
    code >>= 1, res <<= 1;
  } while (--len > 0);
  return res >> 1;
}

/* ===========================================================================
 * Flush the bit buffer, keeping at most 7 bits in it.
 */
local void bi_flush(s)
     deflate_state *s;
{
  if (s->bi_valid == 16) {
    put_short(s, s->bi_buf);
    s->bi_buf = 0;
    s->bi_valid = 0;
  } else if (s->bi_valid >= 8) {
    put_byte(s, (Byte)s->bi_buf);
    s->bi_buf >>= 8;
    s->bi_valid -= 8;
  }
}

/* ===========================================================================
 * Flush the bit buffer and align the output on a byte boundary
 */
local void bi_windup(s)
     deflate_state *s;
{
  if (s->bi_valid > 8) {
    put_short(s, s->bi_buf);
  } else if (s->bi_valid > 0) {
    put_byte(s, (Byte)s->bi_buf);
  }
  s->bi_buf = 0;
  s->bi_valid = 0;
#ifdef DEBUG
  s->bits_sent = (s->bits_sent+7) & ~7;
#endif
}

/* ===========================================================================
 * Copy a stored block, storing first the length and its
 * one's complement if requested.
 */
local void copy_block(s, buf, len, header)
    deflate_state *s;
    charf    *buf;    /* the input data */
    unsigned len;     /* its length */
    int      header;  /* true if block header must be written */
{
  bi_windup(s);        /* align on byte boundary */
  s->last_eob_len = 8; /* enough lookahead for inflate */
  
  if (header) {
      put_short(s, (ush)len);   
      put_short(s, (ush)~len);
#ifdef DEBUG
      s->bits_sent += 2*16;
#endif
  }
#ifdef DEBUG
  s->bits_sent += (ulg)len<<3;
#endif
  while (len--) {
    put_byte(s, *buf++);
  }
}

